Analyzing and sensing systems for yarn feeders are known in the art. Also known is the use of radiation emitting and radiation receiving members for establishing the presence of yarn on the spool body in a yarn feeder. In these, use is made of evaluating circuits for determining the presence of yarn stores located on the spool body and regulating the number of turns of the yarn feeder as a function of the evaluation. Reference may be made here, inter alia, to European Published Patent Application EP 192 851 and German Published Specification 2 609 973.
A general demand exists with yarn feeders to effect a reliable sensing and analyzing function. Among other things, the problem depends on whether or not the yarn store supporting unit or body is subject to vibration. With a body subject to vibration the aim here is to ensure that the unit is arranged in the yarn feeder in such a way that when the yarn feeder is in operation, the unit can vibrate or oscillate owing to mechanical phenomena and oscillations. The function of the sensing and analysing system must also take account of tolerances which exist in the component parts of the yarn feeder and its assembly, and there are problems in making the sensing and analyzing systems independent of any variation parts of the yarn feeder. In some designs there is a demand for using relatively large tolerances between the assembly positions of the various parts of the yarn feeder. Another demand is for the facility for assembling the parts included in the sensing and analyzing system in a modular arrangement. This gives rise to problems in establishing radiation paths inside the modular arrangement which give small overall heights.
If an imaging system, for example, is used for sensing and/or analysis, there is a limited area in which a sufficiently sharp image required for the initiation is obtained. In the case where a radiation source outside the unit/body is used for emitting the beam from outside against the yarn, there are the problems of effective indication in connection with the yarn feeder.
Demands may arise with the sensing and analysing function for the use of a contact image function, imaging function with object lens or shadow image sensing. Various possibilities exist with regard to this and examples include the use of refracting optics in the unit/body, mirror optics in the unit/body, optics outside the unit/body or a function in which the yarn is used as the dispersing/reflecting element in the identification function.
If refracting optics are used, for example, in the unit, there is a decided problem in getting away from the effect of oscillations in the unit. The same goes for mirror optics in the unit/spool body. With optics outside the spool body there are problems with obtaining a sufficiently good focus from the optics without making the mechanical tolerances too stringent.
The yarn feeder must be capable of working with various types of yarn and yarn diameters. When detecting fine yarns it should be possible to use imaging optics in order to obtain small measuring points, for example measuring points in the order of 30-100.times.10.sup.-5 m (30-100 .mu.m).
In certain cases, there are great demands that the sensing and analyzing system should be largely insensitive to dust and other airborne particles. From this there stems the demand in some cases to be able to use the actual yarn in the cleaning function, i.e. as the yarn turns pass over the yarn store supporting surface of the spool body, the yarn must be capable of keeping this free of dust so that this does not stick and spoil the result.
In connection with this, problems may arise in arranging an effective indication function in close connection with the yarn store supporting surface. It should be possible to arrange the illuminating and receiving members uncritically in connection with the surface.
The energy supply and measuring results from the members handling the sensor elements must also be arranged reliably in the various existing assemblies.
The present invention proposes a device which solves all or some of the problems indicated above. What may be regarded, among other things, as the characteristic feature of the new device is that at least one sensor element is located in the unit/spool body in a, from a yarn detection standpoint, uncritical relationship to the unit's yarn transporting surface and the yarn turn travelling forward on this. In addition, transmitting members are designed to relay information by wireless means from each sensor element in the unit in unprocessed or processed form to the receiving members located outside the unit/spool body. The unit/spool body is energy self-sufficient and/or can be supplied with energy by wireless means and emits energy to each sensor element and the said wireless transmission by means of an energy emitting/energy converting member located in the unit, for example in the form of a battery, generator, inductive winding, capacitive member, etc. The characteristics may be supplemented or exchanged in cases where one or more of the sensor elements consists of an optical sensor element which together with one or more optical emitting elements forms part of an arrangement on a unit exposed to vibration. The arrangement in this case is designed to significantly reduce the effect of the unit's vibration on the sensing and/or analysis results.
In one embodiment, sensor elements arranged in the unit/spool body are placed in close connection with the unit's yarn transporting surface. Close connection here is taken to mean a distance equal to approximately one yarn diameter. The sensor elements are preferably placed in successive rows, they can possibly also occupy different positions in the direction of the angle of rotation. The information which is thereby obtained from the sensor element/sensor elements can be processed by means of circuits which are arranged in the unit and, for example, comprise a microprocessor which is connected to or comprises memory storage members. Measured value converting elements can also be included and are then preferably connected to the microprocessor. The sensor elements and their associated equipment are preferably arranged on an assembly board. This in turn can be arranged in a slot in the unit/spool body. The sensor elements can thereby be placed on the board in such a way that they are positioned in connection with or on the actual board's edge. The board is thereby arranged essentially radially in the spool body, which means that the sensor elements are in close connection with, for example right on the yarn store supporting surface which can be homogeneous or formed from extended (for example finger-shaped) members regularly distributed along the arranged periphery or circumference.
In a preferred embodiment, one or more of the sensor elements operates with a capacitive function where each yarn storage turn brings about an indicatable modification. In this case each sensor element may comprise coverings/electrodes, one or more first electrodes of which are connected/connectable to a high frequency signal and one or more other coverings/electrodes have the function of an antenna/antennae. The sensor elements also comprise the modification on account of yarn passage sensing members which may be composed of a differential amplifier function which emits an indicating signal at each yarn turn passage.
In a further embodiment, one or more radiation emitting elements are used which are arranged in the spool body. The arrangement in this case works by radiation reflection against the yarn or the contrast effect against a background in which the yarn store, if so desired, can be formed by means of an object lens. In a further embodiment, one or more radiation emitting elements can be arranged outside the unit, for example in or on the yarn feeder's rail. The arrangement in this case functions by contact image sensing, imaging by means of an object lens or shadow image reproduction. The sensor elements can thereby be of a discrete and/or integrated type.
In a preferred embodiment, the sensor element is included in a component which is constructed separately and functions as a modular unit. In addition to each sensor element, the component comprises a limiting surface, fixed firmly in relation to the sensor element/sensor elements, via which optical radiation passes. the component is arranged or can be arranged in the unit/spool body so that the limiting surface is essentially, preferably precisely, connected to the unit's yarn supporting surface. The component may also comprise one or more radiation emitting elements (light emitting diodes, semiconductor laser, etc.). In the case in which the sensor elements and their associated signal evaluating equipment are placed in the unit, this is designed with wirelessly operating members by means of which it can transmit to receiving members outside the unit. Transmission may thus be by optical, inductive and/or capacitive means. The system can detect individual yarn stores, for example the first and last turns on the unit's yarn store. The system can function as a take-off sensor system and thereby uses information from each sensor element. Logic circuits connected to the sensor elements are thereby designed to draw conclusions from the sensor element information during the yarn's take-off process. The system can thereby be designed to take account of the cases in which the yarn feeder uses a yarn separation function in which the yarn store turns travel over the transporting surface with space between them. In one embodiment, sensor element tolerances critical for the detection of the yarn are built into this during manufacture of the sensor element and/or the parts comprising a sensor element.
The diameter and/or color of the yarn can be indicated with a view to predicting and drawing conclusions on the quality of the yarn, yarn breaks, color shade distribution, weak points, lumps, knots, etc.
In one embodiment, one or more sensor elements, the energy emitting/energy converting members and the transmitting members (transmitter and receiver) are arranged on a common board which can be fixed in the unit. The said energy emitting/energy converting members can be connected to a rectifier (not demanded in the case of a battery) which in turn is connected to a filter member. The transmitting members can operate with radiation, for example infra-red radiation. The transmitting members comprise receivers and transmitting units applied to the board which are tuned to corresponding receiving and transmitting members outside the unit. The latter members are arranged on the yarn feeder, for example in a rail belonging to the yarn feeder. The yarn feeder also comprises members for receiving sensor element information. The yarn feeder comprises circuits which can receive and where necessary process and further relay information to a superior control member for the yarn feeder and/or textile machine.
In one exemplary embodiment, a number of discrete radiation emitting elements are arranged outside the unit, for example in the rail of the yarn feeder. A sufficiently large part of the unit is to be illuminated with radiation emission in order to ensure that the problem with vibrations is solved; the spool body/unit can typically vibrate at approximately 20 Hz. In the cases where reading has to be done faster, provision is made for adequate illumination over the entire surface. A number of discrete sensor elements corresponding to the number of radiation elements is arranged in the unit. The sensor elements are preferably included in an assembly part which is arranged with a non-transparent surface largely coinciding with the units' yarn transporting surface, the non-transparent surface being provided with recesses/apertures/windows through which the radiation from each radiation emitting element can pass. A radiation emitting diode can be arranged outside the unit, for example in the rail of the yarn feeder. An integrated sensor element (array) can thereby be arranged so that it receives the radiation set up via an object lens and where necessary a mirror for deflecting the radiation path past the centre axis of the unit, a short integrated sensor element (for example with a length of approximately 25 mm) being able to be used to indicate a yarn store which exceeds the length of the sensor element by, for example, 2-3 times.
In a further embodiment, a radiation emitting element is arranged outside the unit, for example in the rail of the yarn feeder. An integrated sensor element (array) is connected to the unit's yarn transporting surface. On this surface the sensor element supports a fibre optic plate of a type known in the art. One or more of the said radiation emitting elements may be of the type which functions with monochrome light, for example semiconductor laser, IR diode with optical bandpass filter, etc.
Optimum solutions for the sensing and/or analyzing functions can be brought about by means of the measures suggested above. For example, by arranging sensor elements in close connection with the yarn transporting surface these can be positioned near to the yarn travelling forward. This provides the facility for arranging the yarn transporting surface so as to prevent the accumulation of dust. The arrangements can be arranged for feeding yarn with very small yarn diameters and insensitivity to vibrations in the unit/spool body. Purely capacitive solutions can be used, which is advantageous in the case of yarns which have the ability to influence the dielectric constant in the capacitive structure. The invention offers the facility for a wide liberty of choice when it comes to using optics with optical parts in and outside the spool body. Relatively speaking, technically simple and economically advantageous structures can be arranged, as well as more advanced and extremely accurately functioning arrangements.
By using translucent or transparent covering parts/windows the detector arrangement can be protected as such. A fixed distance between the yarn and the detector can be built in with the said modular unit in an uncritical way (the limiting surface is placed on the yarn transporting surface). Small distance tolerances can be built into the modular unit which makes it possible to have small overall heights on the modular unit. Imaging optics can be used where a sharp image and hence a high resolution is obtained by the passage of the yarn (even with small yarn diameters, for example 30 .mu.m). The indicating members can be arranged close to the yarn transporting surface (less than one yarn diameter). Placing the detector in the spool body provides the facility for structures which are largely insensitive to vibrations. Illumination (radiation emission) from the body/under the yarn transporting surface via translucent/transparent parts provides great insensitivity to dust and wear and tear. Illumination from below also provides considerable insensitivity to vibrations in the unit/spool body. Illumination from below also makes it possible to work with reflected light against the yarn. By placing the illumination outside the unit, insensitivity to vibrations is achieved by using a sufficiently broad and powerful radiation source. Placing the sensor in the spool body opens up quite generally the facility for working at a certain distance from the yarn. The sensor can be arranged in close connection with or in essential contact with the yarn. When using radiation/light guides these are preferably arranged directly against the yarn. If working at a distance from the yarn the yarn is imaged on the detector surface and it is not necessary to use any screen. The sensor senses only at a predetermined point. One method of achieving an appropriate solution to the problems formulated is to use imaging optics with an integrated measuring point. Another method is to use radiation guides which go up to the yarn with very close contact with the latter. Further advantages are obtained by also arranging the illumination in the unit. An array unit with, for example, 1024 detection points can be used. The entire yarn store can be imaged in a like manner. Each pixel can cover approximately 100 .mu.m and the yarn storage length can be practically covered by approximately 0.1 meters.